JPS5835315A - Simultaneous removing method of hydrogen chloride and sulfur oxide from combustion furnace - Google Patents

Abstract

PURPOSE:To enable to remove hydrogen chloride and sulfur oxide contained in combustion gas, simultaneously, easily, and efficiently, by adding calcium compound to the gas, in case that a material to be burnt, containing chlorine content and sulfur content, is burnt in a combustion furnace. CONSTITUTION:When a material to be burnt is burnt, first of all, a calcium compound and a material to be burnt are fed into a fluidized bed part 4, respectively, from a feeder port 3 on the side wall of a fluidized bed combustion furnace 15, for instance, by the intermediary of each hopper 1 and 2. On the other hand, combustion air 7 is fed into the furnace 15, passing through an air inducing chamber 8 and an air dispersing plate 9. With such an arrangement, ion oxide and hydrogen chloride generated in the fluidized bed part 4 during combustion are absorbed by calcium compound, which is discharged from a discharge port 5 as waste absorbent. Waste gas is discharged from a discharge port 10, and dust is separated from the waste gas 12 by a dust collector 11. With such an arrangement, hydrogen chloride and ion oxide contained in combustion gas can be removed from the gas, simultaneously, easily and efficiently.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention is capable of simultaneously and efficiently removing hydrogen chloride and sulfur oxides contained in the generated combustion gas when combustible materials are combusted in a combustion furnace such as a boiler or an incinerator. It relates to a method of removal.

With the growing trend towards resource conservation, the development of new technologies that more effectively utilize fuel resources such as coal, various wastes, and low-grade fuels as energy is being widely promoted. In developing such technology, one of the important technical issues is to improve energy recovery efficiency and to make waste gas pollution-free.

Generally, petroleum, coal, municipal waste, and their thermal decomposition products contain impurities such as sulfur, nitrogen, and chlorine. These components change into sulfur oxides (mainly SO□), nitrogen oxides, and hydrogen chloride through combustion, causing air pollution. Among these pollutants, nitrogen oxides can be reduced to some extent by improving combustion technology and controlling combustion conditions, while sulfur oxides and hydrogen chloride can be reduced by improving combustion technology. It is impossible to measure. Therefore, at present, the wet absorption method using lime is generally used for sulfur oxides, and the wet absorption method using caustic soda as an absorbent for hydrogen chloride. However, not only does the cost of treatment facilities increase, but also the energy recovery efficiency decreases.We have been conducting various studies on the combustion of coal materials, and have found that when combustion is performed in the presence of calcium compounds such as 1-metal calcium carbonate, The chloride water elements and sulfur oxides generated by combustion are efficiently absorbed and removed by calcium compounds at the same time.
In particular, the absorption effect of sulfur oxides is particularly important when burning a combustible material containing sulfur oxides in a combustion furnace.The combustible material in the present invention may be any combustible material. , petroleum-based and gas-based fuels, municipal waste and its pyrolysis products, and other wastes. The combustible material used in this invention contains impurities as follows:
It contains sulfur as an essential component. The presence of chlorine is rather preferable in terms of increasing the efficiency of sulfur oxidation absorption by calcium compounds. Therefore, if the material to be burned does not contain only sulfur, the weight percentage of sulfur oxides can be increased by mixing and burning the material containing chlorine. The ratio of sulfur and chlorine contained in the material to be burnt is not particularly restricted, and is preferably set such that the electrical ratio C1/S of chlorine to sulfur is 0.1 or more, in terms of the amount of elements.

Calcium compound combustion temperature used as an absorbent in the invention (
Any material may be used as long as it shows reactivity with sulfur oxide and hydrogen at a temperature of 700 to 900°C, such as calcium oxide, hydroxide column, calcium carbonate, and the like. Calcium carbonate is particularly preferred from the viewpoints of being inexpensive, being a stable substance, and easily maintaining its granular form. The proportion of the calcium compound to be used may be at least twice, preferably three times or more, the theoretical amount for the sulfur oxide and hydrogen chloride, and this calcium compound is usually continuously used together with the material to be combusted. It is then put into the combustion furnace.

Since the absorption and removal of sulfur oxides and hydrogen chloride for calcium compounds according to the present invention is carried out in a combustion furnace, there is no need to install large-scale attached equipment such as a garden, which is required in conventional wet processing. In addition, sulfur oxides and hydrogen chloride are removed in the combustion furnace, which has the advantage of suppressing corrosion in the combustion furnace.Furthermore, in the case of boilers,
Since corrosion of the heat recovery section can be reduced, it is also possible to increase the superheated steam pressure and improve energy recovery efficiency.

Next, the present invention will be explained with reference to the drawings.

In the drawings, reference numeral 1 indicates a calcium compound hopper, and 2
are fuel (combustible material) hoppers, and through these hoppers, the calcium compound and fuel enter the fluidized bed section 4 from the supply port 3 on the side of the fluidized combustion furnace 15. On the other hand, combustion air 7 is supplied through an air guide chamber 8 and a distribution plate 9. The sulfur oxides and hydrogen chloride generated by combustion in the fluidized bed section 4 are absorbed by calcium compounds, and the calcium compounds that have absorbed the sulfur oxides and hydrogen chloride are discharged to the discharge port 5 as a waste absorbent.
is discharged from. The flying dust passes through the exhaust gas outlet 10 and is separated from the exhaust gas 12 by a precipitator 11 . 1
3 and 14 are heat transfer tubes for heat recovery.

As described above, in the present invention, there is no need to install special equipment for absorbing hydrogen chloride and sulfur oxides, and the calcium compound can also be used as a fuel fluidization medium. The absorption reaction temperature, that is, the temperature of the fluidized bed section 4 is preferably in the range of 700 to 900°C. In order to improve the dehydrochlorination rate and the desulfurization rate, it is necessary to increase the supply ratio of calcium compounds to fuel, but the calcium compound supply ratio is usually a molar ratio of Ca/(Ct2+S) of 2 or more, preferably 3. That's all.

Note that the present invention is naturally applicable not only to fluidized combustion but also to desulfurization and dechlorination in other types of combustion.

Next, the present invention will be explained in more detail with reference to Examples.

EXAMPLE Let's burn the thermal decomposition products of municipal waste at 800°C using a fluidized combustion furnace as shown in the drawings. In this case, without an absorbent, the waste gas contains 1200 ppm of hydrogen chloride and 500 ppm of sulfur oxide (80□). On the other hand, when calcium carbonate with a Ca/(C42+S) molar ratio of approximately 2 is mixed, hydrogen chloride becomes 450 ppm.
, sulfur oxides were reduced to 50 ppm, and the respective absorption rates were about 60 and 90 inches. Similar results were also obtained when calcium oxide was used instead of calcium carbonate.

For comparison, when fuel 3 containing substantially no chlorine content but containing the same amount of sulfur was burned in the same manner as above, the sulfur absorption rate was approximately 60%, and the coexistence of chlorine content was j4-It was observed that the sulfur oxide absorption rate was lower than that when the municipal waste pyrolysis product was combusted.

[Brief explanation of drawings]

The drawing is an explanatory diagram of an apparatus for carrying out the present invention. l... Calcium compound hot, 2... Fuel hole, 3... Supply port, 4... Fluidized bed section, 5...
Exhaust port, 6... Exhaust calcium compound, 7... Air, 8... Air guide chamber, 9... Dispersion plate, lO... Exhaust outlet, 11... Dust collector, 12 ...waste gas, 13,
14... Transfer tube, 15... Fluidized combustion furnace. Patent ratio: Makoto Ishizaka, Agency of Industrial Science and Technology - Designated agent: Toshio Sato, Director, Hokkaido Industrial Development Testing Institute, Agency of Industrial Science and Technology

Claims (1)

[Claims] (1) When burning materials containing chlorine and sulfur in a combustion furnace, hydrogen chloride and sulfur oxides generated by combustion are removed by burning the materials in the presence of calcium compounds. A method for simultaneously removing hydrogen chloride and sulfur oxides in a combustion furnace, characterized by simultaneously absorbing and removing the calcium compound and increasing the rate of absorption and removal of sulfur oxides.